Brain syndromes/diseases (e.g., Parkinson, Alzheimers, etc.) may be treated with electrical leads (wires) that extend deep into a patient's brain and stimulate a selected portion of the brain with electricity. Traditionally, the electrical leads extend through one or more burr hole, which are holes made in a patient's skull. The industry has found that simply extending leads through a burr hole makes it difficult to maintain the leads' proper position over time. As such, burr hole coverings were developed to cover open portions of the skull and assist in maintaining the leads' positions.
An example of a conventional burr hole covering is a burr hole plate. Burr hole plates are often thin, circular immobile plates having one or more holes therein. After a burr hole is drilled, the plate is placed on the skull such that one of the holes within the plate lines up with the burr hole. The distal portion of the lead is placed into the proper position within the brain and the proximal portion of the lead exits the burr hole and is strung through the hole of the plate prior to the plate being mounted to the skull. Thereafter, the skull plate is mounted to the skull around the burr hole via screws, and it is expected that the plate will hold the lead in position.
While the burr hole plate may help maintain the lead's position, the inadaptable design has left much to be desired. The hole within the plate is fixed during manufacturing, but unfortunately, surgery is an inexact and sometimes unpredictable procedure. Only after a surgeon has removed necessary portions of the patience's scalp, drilled one or more holes into the patience's skull, analyzed and determined an optimal lead diameter, and positioned the lead deep within the patient's brain, will the doctor be able to precisely determine whether the hole within the burr hole plate is of the optimal diameter and in the optimal position within the plate. At times, the determined optimal lead diameter proved to be too large to be supported by the burr hole plate and the optimal burr hole's position did not line up with a hole within the burr hole plate.
The industry has attempted to reduce the inadaptability of the burr hole plate design by designing the plate with holes that are oversized, thereby ensuring that the hole of the plate is able to accommodate the lead a surgeon decides to use. However, some surgeons decide to use leads that are thinner than the oversized hole, and ill-fitting holes cause the leads to shift over time and lose their optimal positioning. Substantial lead shifting necessitates additional procedures to correct the shift, which increases risk to patients, decreases effectiveness of the procedure, and increases costs for all. Further, oversized holes cause portions of the skull to remain exposed and unprotected. This is certainly a drawback considering covering open portions of the skull is one of the functions of the burr hole covering.
The industry also attempted to reduce inadaptability of the burr hole plates' design by designing the plate with several holes of various sizes that are located at various locations within the burr hole plate. This attempt to fix the problems of burr hole plates has led to more frustration. Referring back to the surgical example above, after having determined the size and placement of a lead, the determination may be thwarted by the burr hole plate when the hole of proper size is located at the wrong location within the plate. Again, the surgeon resorts to selecting a hole that is the closest match to the patient's needs, but ill-fitting holes cause leads to shift over time and lose their optimal positioning. As explained above, ill-fitting holes may cause additional surgeries and/or leave portions of the skull unprotected.
Further, the immobility of burr hole plates cause the installation to be tedious. During installation, after having positioned the lead deep within the brain, the surgeon threads the lead through the hole within the plate and thereafter must hold everything steady while drilling the plate into the skull. Holding steady the position of a lead, a plate, a drill, and screws all at the same time has been proven to be quite difficult. Often the position of one or more components is lost during the installation process, thereby causing the process to be started over.
In response, some in the industry have moved to a two component design, for example, a two component burr hole clamp system. Typically, a burr hole clamp system includes a hard anchor (e.g., titanium clamp) that clamps a soft inner sleeve (e.g., silicon plug). The anchor has an open state and a closed state. Further, the anchor includes a hole through which a lead may pass. The hole is larger in the open state and smaller in the closed state. During installation, a surgeon may drill a burr hole. Then, the distal end of a lead may be positioned deep within the brain, and the proximal end of the lead may be threaded through the soft inner sleeve of the system. Thereafter, the anchor, in its open state, is positioned around the soft inner sleeve at the burr hole. The anchor is transitioned to its closed state, wherein the anchor clamps the soft inner sleeve through which the lead is threaded. The soft inner sleeve functions similar to an o-ring gasket seal, which holds the lead steady, prevents shifting, and provides skull coverage even when the hole of the anchor is larger than a surgeon selected lead. After the anchor clamps the soft inner sleeve, the anchor is mounted to the skull via screws.
While the two component burr hole clamp system assists with the lead shifting problems described above, the design has left much to be desired. For instance, installation of the burr hole clamp system is even more tedious than burr hole plates. As explained, after having positioned the lead deep within the brain, the surgeon threads the lead through the soft inner sleeve, positions the anchor around the sleeve, and positions the anchor on the skull at the burr hole. Thereafter, the surgeon must hold everything steady while drilling the anchor into the skull. Holding steady the position of the lead, the soft inner sleeve, the anchor plate, the drill, and the screws all at the same time has been proven to add difficulty to installation of simple burr hole plates. Often the position of one or more components is lost during the installation process, thereby causing the process to be started over.
In an effort to reduce the complexity of burr hole clamp systems' installation, some in the industry designed an anchor that partially mounts to the skull before positioning the lead and the soft inner sleeve. The thought being, if the anchor is at least partially drilled into place, then one less component must be held steady during the final installation of the lead and soft inner sleeve. To achieve this goal, the anchor includes a hinged portion that provides the open and closed states of the anchor. During installation, the anchor is mounted to the skull around the burr hole via screws. The hinged portion of the anchor is not yet mounted to the skull. Then, after having positioned the lead deep within the brain, the surgeon threads the lead through the soft inner sleeve, positions the soft inner sleeve within the anchor, closes the hinged portion of the anchor, and mounts the hinged portion of the anchor to the skull via screws. The partial installation of the anchor prior to positioning the lead and soft inner sleeve reduces some of the installation complexity, but still leaves much to be desired.
Due to the two component design, a surgeon is still tasked with steading multiple component pieces in position while installing the final screws. Often the position of one or more components is lost during the installation process, thereby causing the process to be started over. Further, the soft inner sleeve typically extends into and out from the anchor. Patients complain that the burr hole clamp system is uncomfortably thick, which makes them unpopular. In embodiments, after a burr hole system is mounted to the skull, skin is grown over the anchor and soft inner sleeve to provide protection from infection and minimize the appearance of the implant. In sub-dermal systems, the thickness of the implant is of great importance because the location of the sub-dermal implant appears to be a deformity. The two tiered design of two component systems cause the burr hole covering to be significantly thicker than burr hole plates. Due to this thickness, a patience's apparent deformity is a source of great embarrassment and causes some patients to avoid the procedure despite its neurological benefits. Further, while most burr hole coverings are abrasive to the dermis and subcutaneous tissues, the increased thickness and complexity of two component systems cause them to be increasingly abrasive. Moreover, the soft inner sleeve causes increased thickness making it harder for patients to comfortably lay down and/or rest in high back seats (e.g., airplane seats). Further still, in order to ensure the proper sealing effect, the soft inner sleeve typically extends into the burr hole. Thus, the two component system causes abrasiveness and irritation above and below the skull. In short, two component burr hole plugs cause physical and emotional discomfort to patients.
In an effort to solve the problems caused by burr hole plates and two component burr hole clamp systems, some in the industry have moved to burr hole plugs. Burr hole plugs are typically a two component device having a plug base that mounts to the skull, and a retainer that maintains the lead's position. When installed, the retainer mounts into the plug base, which holds the retainer in place. The plug base is mounted to the skull using screws and has an aperture in its center. When mounted, the aperture is positioned such that the aperture exposes a burr hole therethrough. After mounting the plug base to the skull, a lead may extend through the aperture, into the burr hole, and be positioned into the brain. The size of the burr plug's aperture is purposefully bigger than any expected burr hole, and instead, is sized to receive the second component, a retainer, therein. The retainer is then installed by clamping the lead and being fitted (e.g., snapped into) into the aperture of the plug base. The burr plug holds steady the retainer, which in turn holds the lead in place.
This two component design of the burr hole plug reduces installation complexity; however, the design leaves much to be desired. As with the clamp system, the two component design makes manufacturing and packaging more complicated and expensive. Because the retainer must perfectly seat into the plug base to be held securely, the fitting components of the retainer and the fitting components of the plug base have to be manufactured with extreme precision. Minimal manufacturing error is sufficient to cause the device to fail. Further, since the two different components are manufactured using two different machines, manufacturing facilities have to develop techniques to ensure the proper retaining component is properly packaged with the proper plug base. Improper packaging leads to malfunctioning burr hole plugs being delivered to a surgical room, which can be costly to the patient, surgeon, and surgical facility alike.
Further still, the two component burr hole plugs are uncomfortably thick, which makes them unpopular with patients. Due to this thickness, a patient's apparent deformity is a source of great embarrassment and causes some patients to avoid the procedure despite its neurological benefits. Further, while all burr coverings are abrasive to the dermis and subcutaneous tissues, the increased thickness and complexity of burr hole plugs cause them to be increasingly abrasive. Moreover, burr hole plugs' increased thickness makes it harder for patients to comfortably lay down and/or rest in high back seats (e.g., airplane seats). In short, burr hole plugs cause physical and emotional discomfort to patients.
Further still, a problem common to burr hole plates, two component burr hole clamp systems, and burr hole plugs is lead projection. When a lead exits a fully installed burr hole cover, the space of the burr hole covering causes the lead to project out away from the skull. Moreover, the thicker the burr hole cover, the larger the lead projection. The lead projection causes the implant system to be even thicker, which as explained above, causes patient embarrassment and discomfort. In embodiments wherein the lead projection is sub-dermal, the lead projection causes additional lumps, abrasiveness, and irritation. In embodiments wherein the lead projects out of the skin at the burr hole covering, the lead projection runs the risk of being caught in something (e.g., a hair brush) and shifting from its precise position deep within the brain. In short, traditional burr hole cover systems have yet to provide a satisfactory solution to lead projection problems.